KVM: x86/mmu: Don't mark "struct page" accessed when zapping SPTEs

KVM: x86/mmu: Don't mark "struct page" accessed when zapping SPTEs

Don't mark pages/folios as accessed in the primary MMU when zapping SPTEs,
as doing so relies on kvm_pfn_to_refcounted_page(), and generally speaking
is unnecessary and wasteful.  KVM participates in page aging via
mmu_notifiers, so there's no need to push "accessed" updates to the
primary MMU.

And if KVM zaps a SPTe in response to an mmu_notifier, marking it accessed
_after_ the primary MMU has decided to zap the page is likely to go
unnoticed, i.e. odds are good that, if the page is being zapped for
reclaim, the page will be swapped out regardless of whether or not KVM
marks the page accessed.

Dropping x86's use of kvm_set_pfn_accessed() also paves the way for
removing kvm_pfn_to_refcounted_page() and all its users.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-83-seanjc@google.com>